Correcting for a 3-minute offset every few millenia seems easier than trying to understand all this minutia about wobble and aquifer management and whatever else goes into a leap second.
I say we let it reach 15 minutes then countries can solve it themselves by shifting timezone by 15 mins. Since making sure solar noon matches noon on the clock, is the point of timezones existing in the first place
We'll feel awful silly having made any leap seconds if the robots kill us all in the next decade.
More seriously -- all of today's computers and probably all of today's software (not to mention many scientific and governmental institutions) will be gone in 500 years. Does it make sense to plan too far ahead?